Battery-depolarizer.



entree erases PATENT enrich.

HA3 E. HQLMES, OF LAKEWOOD, OHIO, ASSIGNOR, BY IVIESNE ASSIGNMENTS, T0

NATIONAL CARBON GGMPANY, INC., A CORPORAIIQBT OF NEW YOBJZ. I

BATTERY-DEPOLABIZEB Ito Drawing.

T 0 all whom it may concern;

Be it known that I, MAJon E. Homzns, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement inBa-ttery-Depolarizers, t which the following is a full, clear, and exact description.

My invention relates to depolarizers for electric batteries and is primarily adapted for that type of electric battery known as dry cells.

Dry cells have for a. long time been constructed with pyrolusite as 'depolarizer. This material is much too dense for etl iclent action, and does not pack into the dry cell container as readily as desired. Pyrolusite also contains impurities that not only occupy space that should contain depolarizer, but also injuriously afi'ect the cells action. It is not suiliciently active, chemically, to react with all the hydrogen when the cell is subjected to severe service, as when used in flash light batteries. It is the object of my invention to treat the natural mineral pyrolusite so as to overcome the above difficulties.

vBefore incorporating pyrolusite in a dry cell containing the usual carbon electrode and zinc can, I sub ect it to the actlon of sodium hydroxid, or other hydroxid, under,

pressure. Below 175 ,the rate of the reactionis slow, but if pyrolusite is heated to this temperature at normal atmospheric pressure it is reduced to a lower oxid, namely Mn fi Since this lower oxid is not reduced by hydrogen atordinary temperatures, it is of no value as a depolari zcr, and the above treatment must take place under sufficient pressure to'prevent the reduction of the pyrolus ite. It has been found-that the most suitable temperature for bringing about the reaction is approximately 188 C. When a solrtion of sodium hydroxid is heated with air and pyrolusite under pressure, the latter is hydrated. While this takes place in one continuous -re'action, itnevertheless probably takes place in two. stages as shown bythe following equations:

. QNaOH+MnO,+:Na Mn@,-+H 0 The material can also be made b mixin B powdered sodium hydrorgid, or other hy= Specification of Zetters Patent.

Application filed September 10, 1914;. Serial No. 861,074.

oxidizing agent such as a chlorate perchlorate, nitrate, etc., and heating, preferably until fusion takes place. This produces sodium nianganate which is then converted into the hydrated peroxid by crushing and treating with steam. It will be apparent that the modified process produces the desired result in two entirely separate steps. The fusion of the hydroxid with the pyrolusite produces the reaction set forth in the first equation previously 'given, While the treatment of the sodium manganate with steam produces the reaction set forth 'in the second equation. The modified process is claimed in my divisional application tiled September 15, 1916, Serial No. 120,273.

The pyrolusite, after being treated in either way, is transformed into a Very fine powder of less density and higher compressibility than the original material. This.

not only enables it to be better tirmped in the zinc can, but also permits its separation from the impurities in-the pyrolusite which have not been acted upon by the hydroxid solution. These impurities ,are not in such a fine state of division and therefore can be separated from the manganese peroxid by the use of sieves of proper/ mesh.

Pyrolusite', when acted upon by an alkaline solution as described, has much greater activity as a depolarizer, and hence is preferable to the native pyrolusite for dry cell work.

Qinother distinct advantage in the treated product is in its increased absorptive power. The treated material when incorporated in a dry cell as the depolarizer therefore absorbs more electrolyte solution than the natural pyrolusite, which not only increases the en ergy output but also prevehts thepremature drying out of the cell.

T he hydrated material has a slight tendency to react With the zinc chlorid in a dry cell mix to form hydrochloric acid which attacks the zinc regardless of whether the cell is being used or not. acid formed is of course small and it is not objectionable if cells are put into use on heavy service Within a reasonable time after being made, but a long shelf life is of prime importance in certain other uses, and to prevent this reaction I dehydrate the product. This may be done byralcining it to drive 01? the water of hydration, as described in my co-pending application filed December 21;;

The amount of the 1912, Serial No. la-$2,615, which has become Extent No. 1,18%,85ai.

The calcined product has the same acivans tageous physical properties as before caicination, such as fine state of division, greater compressibility and increased absorptive power, etc. These physical characteristics, however not only have their physical. effect When the depolarizer is-useci in a dry cell mix, but also increase the chemical activity .oi the material. Such effect or physical state on chemical activity is Well known in other artsl For instance, coal at ordinary temperatures does not oxidiz but when it is ground ihto fine dust particles its oxi iation is so instantaneous as to cause violent explosions of not infrequent occurrence in coal mines Pyrolusite in an analogous way has undergone an advantageous change in spite of the fact that the calcination probably brings it back into its original chemical 1 form. h

Both the hydrated and dehydrated pyroiusite, that is dehydrated hydrateci-pyroiugancse PBi'OlQid has been made by'treafing certain manganese. s alts with various reagents but the product obtained by my invention is not the same as such artificial product, as various tests show.

Having described my invention, What I claim is:

T he process of purifying pyrolusite and increasing its depolarizing action when used in electric batteries which consists in heating it in a hydroxid solution under pressure.

In testimony whereof, I hereunto-affix my signature in t e presence of Witnesses. x MAJOR E. HOLMES. Witnesses:

H. G. Groves, C. Piano. 

